1. Field of the Invention
The present invention is directed to a gas valve, and more specifically, to a gas valve for use in a gas regulator that allows entry of a compressed gas, but blocks the entry of contaminants into the gas regulator.
2. Description of the Related Art
Scuba tanks generally utilize a pressurized source of breathable gas, such as compressed air as well as mixed gas blends, having pressures in the range of 3,000 to 5000 psi. A two stage pressure reduction system is typically used to deliver the gas to a scuba diver at a pressure that is within an appropriate pressure range for underwater diving. A first stage regulator reduces the pressure of gas from the scuba tank to an intermediate pressure range of about 120 to 140 psi, while a second stage regulator, typically incorporated into a breathing mask, regulates the flow of gas delivered to the diver to a pressure that depends on the depth of the diver in the water.
First stage regulators are generally connected to the scuba tank using one of two types valve connection arrangements: yoke-type connection or DIN valve connection. In yoke-type connection systems, the regulator comprises a round opening that is filled by a metal filter surrounded by a raised collar with an o-ring. The scuba tank has an inlet/outlet tank valve with a small aperture located near the middle of a round recessed area. The raised collar of the regulator valve fits snugly within the recessed area of the tank valve. A hand knob is used to secure the tank valve and to form a seal at the o-ring. With a DIN valve connection, the first stage regulator screws directly into the scuba tank valve outlet opening using either five or seven threads, depending upon the pressure to be contained within the tank. Other, less common, connection arrangements are also available, such as those utilized in technical diving and rebreather units.
The dual stage regulator system is attached to a tank valve using a hand knob with a screw member that is part of the regulator assembly. Once the first stage regulator is attached to the scuba tank, an closed system is formed between the input of the first stage regulator and the input of the second stage regulator that is unexposed to the ambient environment. However, the interior components of the first stage regulator can potentially become exposed to external contaminants such as salt water, fresh water, wash water, airborne particulates, and the like when the scuba tank is not connected to the scuba tank. Such contamination can rust and corrode critical regulator components such as metal air filters and lead to the clogging of small apertures or orifices. This can lead to potentially catastrophic consequences during use of the regulator system due to partial or complete failure of the equipment.
A dust cover is usually attached to the first stage regulator for covering the entrance port of the first stage regulator when the regulator is not attached to the scuba tank, thus preventing the entrance of contaminants into the regulator system. The cover is typically held in place using the same hand knob that is used for attaching the scuba tank. Between or after dives it is, however, easy for the diver to either forget to attach the cover or simply decide this precaution is unnecessary.
In order to avoid this dependence on the diver to protect the internal components of the regulator system by manually attaching the dust cover, it would be beneficial to have a regulator control valve that automatically seals the entrance port of the regulator from contaminants such as water when the scuba tank is disconnected and/or when pressure near the entrance port of the first stage regulator is below a predetermined minimum.
One solution for automatically covering the entrance port of a first stage regulator when the scuba tank is not connected is disclosed in U. S. patent application Ser. No. 09/872,130, which is herein incorporated by reference in its entirety. In this device, a piston is disposed inside the regulator valve near the entrance port. The piston is biased to a closed position that covers the regulator valve entrance port, thereby preventing the entrance of water and/or other possible contaminants when a scuba tanks is not connected. When the scuba tank is connected to the regulator valve and the tank valve is opened, gas pressure overcomes the bias force on the piston, thus opening the regulator valve opens to allow the passage of gas.